As Paul pointed out, max temp was wrong.

Summary for December 2009

Temperature (°C):
Mean (1 minute) 4.3
Mean (min+max) 4.1
Mean Minimum 1.8
Mean Maximum 6.5
Minimum -3.6 day 16
Maximum 13.1 day 06
Highest Minimum 9.5 day 09
Lowest Maximum 0.5 day 19
Air frosts 10

Rainfall (mm):
Total for month 90.3
Wettest day 14.8 day 02
Rain days 24

Wind (mph):
Highest Gust 41.0 day 06
Average Speed 4.4


Pressure (mb):
Maximum 1032.4 day 11
Minimum 981.5 day 22

Days with snow falling 5
Days with snow lying at 0900 7